overriding

问题 In the Scaladoc of class Enumeration#Val, I can read: "A class implementing the Value type. This class can be overridden to change the enumeration's naming and integer identification behaviour." I am puzzled: how do I override a class? Things like override class Val extends super.Val are not permitted. 回答1: There are no virtual classes in Scala (yet), so you can't write override class Val ... , and then be sure that invoking new Val will dynamically choose the right class for the new instance

问题 I have an AlertDialog dlgDetails which is shown from another AlertDialog dlgMenu . I would like to be able to show dlgMenu again if the user presses the back button in dlgDetails and simply exit the dialog if he presses outside the dialog. I think the best way to do this is to override onBackPressed for dlgDetails, but I am not sure how to do that since AlertDialogs must be created indirectly using the Builder. I am trying to create a derived AlertDialog ( public class AlertDialogDetails

问题 I can surely answer to this question by myself writing a dummy test but I want to know what people think about the question. Here it is: Which method will be call when we have both at the same time overloading and overriding? I am only considering Type overloading and not arity overloading and when Type the overload are related. Let me throw you an example: class AA {} class BB : AA {} class A { public virtual void methodA(AA anAA) { Console.Write("A:methodA(AA) called"); } public virtual

问题 I can surely answer to this question by myself writing a dummy test but I want to know what people think about the question. Here it is: Which method will be call when we have both at the same time overloading and overriding? I am only considering Type overloading and not arity overloading and when Type the overload are related. Let me throw you an example: class AA {} class BB : AA {} class A { public virtual void methodA(AA anAA) { Console.Write("A:methodA(AA) called"); } public virtual

问题 This question already has answers here : vector of objects (5 answers) Closed 5 years ago . class classa { public: virtual void foo(); }; class classb : public classa { public: virtual void foo() override; }; void classa::foo() { std::cout << "foo from a" << std::endl; } void classb::foo() { std::cout << "foo from b" << std::endl; } int main() { std::vector<classa> stuff; classa a; classb b; stuff.push_back(a); stuff.push_back(b); stuff[0].foo(); stuff[1].foo(); return 0; } I expected the

问题 I need to check the validity of a coupon code on the checkout/cart page with server-side code. Magento already ships with a similar check in place. However, I need to add one to see if a user is connected or not: what would be the best way to extend/override that action in Magento? I know I can copy the controller PHP file to the /app/code/local/ folder tree, but I'm wondering whether there's a better way to do it. 回答1: Anything besides modifying the core is good in my opinion. With that said

问题 I have a base class which I want to provide some 'base' functionality for methods for all inheriting classes. In my inheriting classes I want to do: public override void Setup() { base.Setup(); } But at the moment it says I have to use the new keyword. How to I have it so I have to use the override keyword? Is there any difference between how it is currently with me using the new keyword and using override ? 回答1: It says so because you have not declared the base method virtual . Once you do

问题 I have an inventory program written to include an array and a method to calculate total cost for all inventory items entered. I now have to include a subclass that overrides the original to include "one unique feature". I created a new file named ItemDetails to set up for the subclasses of the original Item. I need to include one unique feature and calculate the value of the inventory and calculate a 5% restocking fee in this subclass. Do I just transfer some of the relevant lines into the

问题 I am going through a LitJSON library. In the code there are lots of segments like public class JsonData : IJsonWrapper, IEquatable<JsonData> #region ICollection Properties int ICollection.Count { get { return Count; } } #end region For a method I know how overriding/overloading works but in the example above the code reads: int ICollection.Count I'm not familiar with that format for a method signature. Is the coder trying to explicitly state its the ICollection.Count interface? Could you

问题 I've tried to find a laymans definition of addNotify() but I can't really get any answer using Google. As far as I know, when overriding addNotify() in my class, I should call super.addNotify(); and then do whatever else afterward. My question is, does addNotify() run automatically? What is it's purpose and what happens when I override it and furthermore, why would I ever want to override this method? Thank's. 回答1: My question is, does addNotify() run automatically? Yes. The precise where and